Abstract-Wireless channel emulators are important tools for testing radio devices, especially in mobile environments. Wireless network emulators give the same accuracy and control for testing radio network systems that traditional channel emulators give to point to point radio links. Network emulators require many more independent channels than traditional channel emulators. This problem is particularly challenging for the real time channel simulator in the emulator. The challenges of designing a wireless network channel simulator are discussed and a design is presented on a Xilinx Virtex-II Pro FPGA. This channel simulator can model 210 independent channels between 15 nodes with a bandwidth of 90MHz. The performance of the design was verified by measuring transport-layer throughput between 802.11b radios transmitting through the channel simulator.
Abstract-This paper presents a framework for signal-level emulation of propagation effects over generalized fading channels at the scale of entire networks. Network emulation enables research into network-scale systems -which would otherwise be limited to low-fidelity network simulators and one-off field experiments -to use real radio hardware and realistic channel models. Our hardware and software architecture goes beyond previous work in that it supports real-time emulation of a very general and parametric class of channels, which includes vehicular (broadband mobile-to-mobile) and indoor channels in addition to classical stationary-to-mobile and stationary-tostationary channels.
Abstract-The Gaussian quadrature rules (GQRs) are used to construct a wireless fading simulator based on the popular sum of sinusoids (SoS) method. The general statistics of the proposed simulator are given. This simulator is also shown to perform well for important design parameters. An extension of the GQRs is employed to build uncorrelated simulators, which are important in frequency selective and MIMO simulators. These simulation techniques are then applied to the Mobile-to-Mobile (MtM) spectrum and are compared with the best known SoS techniques for the MtM spectrum. Although the proposed method is more complex, the efficiency and accuracy are significantly better than the previously proposed methods.
The evaluation of wireless research is challenging because signals traveling through the ether are affected by the physical environment, including movement by people and objects. As a result, testbed experiments are hard to control and are non-repeatable. We have developed a wireless networking testbed based on digital signal propagation emulation that provides control over the signal propagation environment. The testbed has been in regular use for research and education since early 2007. In this paper we present measurements illustrating the properties of the emulator testbed. We also compare the results of various experiments on the emulator with simulation results to shed some light on when the increased accuracy of the emulator testbed is important. Finally, we use the experience gained on the emulator to identify classes of experiments for which the emulator is well suited, compared with other evaluation platforms.
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